Set-Top Box Audio Video Synchronization via Timestamp Difference Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional set-top boxes often send video data too many or too few times due to frame rate variations in video streams, causing audio and video to become out of sync during transmission.
Innovation Solution
An audio and video synchronization method that calculates timestamp differences between video and audio data, using a master presentation timestamp or vertical synchronization pulse to determine whether to output specific video data, preventing excessive repetition and ensuring synchronization by adjusting output based on predetermined conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If video data is transmitted continuously without synchronization control, then transmission simplicity is maintained, but audio and video become out of sync due to frame rate variations
Solution Approach 1:
The patent implements a feedback mechanism where the set-top box calculates timestamp differences between video and audio data, compares them against threshold values, and adjusts video data output accordingly. The synchronization controller continuously monitors timestamp differences and dynamically controls whether to output current or previous video data based on whether the difference exceeds predefined thresholds, creating a closed-loop synchronization system.
Solution Approach 2:
The patent introduces a synchronization controller as an intermediary component between the video decoder and the output interface. This mediator calculates timestamp differences, compares them against thresholds, and makes intelligent decisions about which video data to output, thereby coordinating between the independent video and audio streams without requiring complex changes to either stream processing.
2Reliability
If video data is output selectively based on timestamp differences, then audio-video synchronization is maintained, but processing complexity increases
Solution Approach 1:
The patent changes the parameter being monitored from simple frame counting to timestamp difference calculation. By using presentation timestamps (PTS) and comparing their differences against threshold values, the system achieves more precise synchronization control. The threshold parameters (first threshold and second threshold) allow flexible adjustment of synchronization sensitivity based on specific application requirements.
Solution Approach 2:
The patent performs preliminary calculations of timestamp differences and threshold comparisons before video data output decisions are made. The synchronization controller pre-calculates whether the timestamp difference exceeds thresholds and determines the appropriate output action in advance, ensuring synchronized output without real-time processing delays.
3Reliability
If all video data frames are transmitted, then complete video information is delivered, but excessive frames cause audio-video desynchronization
Solution Approach 1:
The patent applies partial action by selectively outputting only certain video data frames based on timestamp difference thresholds. When the timestamp difference exceeds the first threshold, the system outputs only specific frames (skipping some intermediate frames) to prevent audio-video desynchronization, rather than transmitting all available video frames. This partial transmission maintains synchronization while delivering sufficient video content.
Data Source
AI summary
An audio and video synchronization method is provided, which includes the following operations: obtaining a first presentation time stamp (PTS) of a first video data and a second PTS of a second video data; selecting a master PTS corresponding to an audio data or to a vertical synchronization (Vsync) pulse; calculating a first timestamp difference value between the first PTS and the master PTS, and calculating a second timestamp difference value between the second PTS and the master PTS; and selectively outputting either the first video data or the second video data according to the first timestamp difference value, the second timestamp difference value, and whether the first video data has been outputted for a predetermined number of times.